Method for making a polyamide film

ABSTRACT

Method for making a film comprising, as sole layer(s), at least one layer L1 consisting of a polyamide composition comprising an aromatic polyamide and an impact modifier, said method comprising extruding the polyamide composition into the film.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/568,612, filed May 5, 2008, which is a U.S. national stageapplication under 35 U.S.C. §371 of International Application No.PCT/US2004/026624 filed Aug. 17, 2004, which claims priority to U.S.provisional application 60/496,011 filed Aug. 19, 2003, the all contentof all these applications being herein incorporated by reference for allpurposes.

FIELD OF THE INVENTION

The invention relates to films made of impact-modified polyamide. Thefilms according to the present invention comprise, as sole layers, (1)at least one layer L1 comprising an aromatic polyamide and an impactmodifier, and, optionally, (2) at least one layer L2 comprising analiphatic polyamide.

Additional advantages and other features of the present invention willbe set forth in part in the description that follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from the practice of thepresent invention. The advantages of the present invention may berealized and obtained as particularly pointed out in the appendedclaims. As will be realized, the present invention is capable of otherand different embodiments, and its several details are capable ofmodifications in various obvious respects, all without departing fromthe present invention. The description is to be regarded as illustrativein nature, and not as restrictive.

BACKGROUND OF THE INVENTION

Polyamide films, such as PA 6, 66, 11, 12 and others are known and areused in a variety of applications. For example, polyamide films are usedto provide chemical, water and fuel barrier properties or as insulativecomponents in electrical applications.

However, there remains a need to improve the performance of polyamidefilms with respect to, for example, its mechanical properties,resistance to water, other solvents and chemicals, electrical insulatingproperties, etc.

SUMMARY OF THE INVENTION

The present invention provides a film comprising, as sole layers, (1) atleast one layer L1 comprising an aromatic polyamide and an impactmodifier, and, optionally, (2) at least one layer L2 comprising analiphatic polyamide. In a preferred embodiment L1 is the sole layer ofthe film. In another preferred embodiment, layers L1 and L2 are indirect contact with one another and are the sole layers included in thefilm. In a further preferred embodiment the film includes, as solelayers, three contiguous layers, in the order L1/L2/L1. In yet a furtherpreferred embodiment the film includes, as sole layers, two or morecontiguous L1 layers. In a further preferred embodiment, the filmincludes, as sole layers, any number of contiguous layers of the order[(L1)_(n)/(L2)_(m)]_(x) where x is any integer of 1 or greater, n is anyinteger of 1 or greater, and m is any integer (e.g., 0, 1, 2, etc.). Inanother preferred embodiment, the film does not contain a fluoropolymerlayer. Where the invention film is a multilayer construction, each ofthe L1 and L2 layers may be the same or different from one another.

The films of the invention may be made in any manner desired from theidentified materials to produce layers L1 and L2, such as by extrusion,such techniques being well known to those of ordinary skill in the art.The size, shape, thicknesses, surface texture, etc. of the inventionfilms are not limited in any way.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an extrusion set up useful to extrude filmsaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

For multilayer construction of three or more layers, the term “innerlayer” is understood to mean the innermost layer(s) of the film. Theterm “outer layer” is understood to mean the outermost layer of thefilm; that is, there are no other layers of the film immediatelyadjacent and external to the outer layer(s). Multilayer filmconstructions have two outer layers. Where the film is constituted by asingle layer, it is termed a “monolayer”.

Polyamide

Polyamides are, generally speaking, polymers containing a repeatingamide (CONH) functionality. Typically, polyamides are formed by reactingdiamine and diacid monomer units (e.g., nylon 6,6), or by polymerizingan amino carboxylic acid or caprolactam (e.g., nylon 6). Polyamides arewell known materials. Polyamides that are useful herein include thosedescribed in U.S. Pat. Nos. 6,531,529, 6,359,055 5,665,815, 5,436,294,5,447,980, RE34,447, 6,524,671 (DuPont), 6,306,951 (BP Corp.) and5,416,189 as well as those sold by Solvay Advanced Polymers under theAmodel® and IXEF® brand names. The invention relates to both aromaticand aliphatic polyamides. The aromaticity of the aromatic recurringunits can come from the diacid and/or from the diamine for polyamidesresulting from polycondensation.

Polyamide Composition L1

The L1 polyamide compositions for films useful herein comprise anaromatic polyamide and an impact modifier.

Aromatic Polyamide

Aromatic polyamides are polymers comprising more than 50 mol % of “Type1” repeating units, based on 100 mol % repeating units in the polymer.Type 1 repeating units have at least one CONH group in the polymerchain. In addition, Type 1 repeating units are characterized in that atleast 30 mol % thereof comprise an aromatic group. Thus, the minimumcontent of aromatic group-containing repeating units in an aromaticpolyamide herein is more than 15 mol % based on 100 mol % repeatingunits in the polymer. Preferably, the aromatic polyamide of theinvention comprises at least 20 mol %, based on 100 mol % of monomersmaking up the polyamide, of monomers comprising an aromatic group.Although not required, such aromatic groups typically originate in adiacid monomer, and include terephthalic acid, isophthalic acid,phthalic acid, etc. In preferred embodiments the aromatic polyamidecomprises at least 30 mol %, based on 100 mol % of monomers making upthe polyamide, of monomers comprising an aromatic group, including 35,40, 45, 50, 55, 60, 65, 70, 75, 80, 85, etc. mol %.

One class of preferred aromatic polyamides are PMXDAs, i.e. aromaticpolyamides comprising more than 50 mole % of recurring units formed bythe polycondensation reaction between at least one aliphatic diacid andmetaxylylenediamine.

The aliphatic diacid can be notably adipic acid.

Suitable PMXDAs are notably available as IXEF® PMXDAs from SolvayAdvanced Polymers.

Another class of preferred aromatic polyamides are polyphthalamides,i.e. aromatic polyamides comprising more than 50 mole % of recurringunits formed by the polycondensation reaction between at least onephthalic acid and at least one aliphatic diamine.

The aliphatic diamine can be notably hexamethylenediamine,nonanediamine, 2-methyl-1,5 pentadiamine, and 1,4-diaminobutane.

Suitable polyphthalamides are notably available as AMODEL®polyphthalamides from Solvay Advanced Polymers, L.L.C.

Among polyphthalamides, polyterephthalamides are preferred.Polyterephthalamides are defined as aromatic polyamides comprising morethan 50 mole % of recurring units formed by the polycondensationreaction between terephthalic acid and at least one diamine.

One class of preferred polyterephthalamides is polyterephthalamidesconsisting essentially of recurring units formed by the polycondensationreaction between terephthalic acid and at least one aliphatic diamine.In the polyterephtalamides of this group, the aliphatic diaminecomprises preferably from 3 to 9 carbon atoms, and very preferably, itcomprises 6 carbon atoms. An example of aliphatic diamine comprising 6carbon atoms is hexamethylene diamine.

A second group of preferred polyterephthalamides arepolyterephthalamides consisting essentially of recurring units formed bythe polycondensation reaction between terephthalic acid, isophthalicacid and at least one aliphatic diamine. In this embodiment, the moleratio of the terepthalic acid and the isopthalic acid can be from 50 to80 (including 55, 60, 65, 70, and 75) for the terepthalic acid and from10 to 40 (including 15, 20, 25, and 35) for the isopthalic acid. Inanother embodiment, the mole ratio can be from 35 to 65 for theterepthalic acid and not more than 20 for the isopthalic acid.

A third group of preferred polyterephthalamides are polyterephthalamidesconsisting essentially of recurring units formed by the polycondensationreaction between terephthalic acid, at least one aliphatic diacid and atleast one aliphatic diamine. In this embodiment, the mole ratio of theterepthalic acid and aliphatic diacid can be from 50 to 80 (including55, 60, 65, 70, and 75) for the terepthalic acid and not more than 25(including 5, 10, 15, and 20) for the aliphatic diacid. In anotherembodiment, the mole ratio can be from 35 to 65 for the terepthalic acidand from 30 to 60 for the aliphatic diacid.

A fourth group of preferred polyterephthalamides arepolyterephthalamides consisting essentially of recurring units formed bythe polycondensation reaction between terephthalic acid, isophthalicacid, at least one aliphatic diacid and at least one aliphatic diamine.In this embodiment, the mole ratio of the terepthalic acid and aliphaticdiacid can be from 50 to 80 (including 55, 60, 65, 70, and 75) for theterepthalic acid; from 10 to 40 (including 15, 20, 25, and 35) for theisopthalic acid; and not more than 25 (including 5, 10, 15, and 20) forthe aliphatic diacid. In another embodiment, the mole ratio can be from35 to 65 for the terepthalic acid; not more than 20 for the isopthalicacid; and from 30 to 60 for the aliphatic diacid.

Another preferred aromatic polyamide useful herein is one made fromterephthalic acid, adipic acid, optionally isophthalic acid, andhexamethylene diamine.

In another preferred embodiment the aromatic polyamide is a polyamidewith at least 50 mol. %, including up to 100 mol %, of recurring unitsobtained by the polycondensation reaction between terephthalic,isophthalic, adipic acid; and at least one diamine, preferably analiphatic one. Within this group, the mole ratio ofterephthalic/isophthalic/adipic acid can be from 50 to 80/from 10 to40/not more than 25. In another embodiment the mole ratio ofterephthalic/isophthalic/adipic acid can be from 35 to 65/not more than20/from 30 to 60. In preferred embodiments the diamine component forthese acid mixtures is HMDA.

In certain embodiments of the present invention, the dicarboxylic acidcomponent used in forming the polyphthalamide comprises a mole ratio ofaromatic dicarboxylic groups in the range from at least about 50 mole %aromatic groups to about 100% aromatic groups. In a preferred embodimentof the present invention, the polyphthalamide polymer comprises fromabout 50 mole % to about 95 mole % hexamethylene terephthalamide units,from about 25 mole % to about 0 mole % hexamethylene isophthalamideunits, and from about 50 mole % to about 5 mole % hexamethyleneadipamide units. Another useful aromatic polyamide is one made fromterephthalic acid, isophthalic acid and an aliphatic amine such as HMDA,for example using a 70/30 ratio of TA/IA. Particularly suitablepolyphthalamides for use in the present invention are available asAMODEL® A-1000, A-4000, A-5000, and A-6000 polyphthalamides from SolvayAdvanced Polymers, LLC. Suitable polyphthalamides for use in the presentinvention are disclosed in previously referenced U.S. Pat. Nos.5,436,294; 5,447,980; and Re34,447 to Poppe et al.

Of course, more than one aromatic polyamide may be used in polyamidecomposition L1.

Impact Modifier

The impact modifiers useful herein are not particularly limited, so longas they impart useful properties to the aromatic polyamide component ofthe invention L1 layer, such as sufficient tensile elongation at yieldand break. For example, any rubbery low-modulus functionalizedpolyolefin impact modifier with a glass transition temperature lowerthan 0° C. is suitable for this invention, including functionalizedimpact modifiers disclosed in U.S. Pat. No. 5,436,294 and U.S. Pat. No.5,447,980. Useful impact modifiers include polyolefins, preferablyfunctionalized polyolefins, and especially elastomers such as SEBS andEPDM.

Useful functionalized polyolefin impact modifiers are available fromcommercial sources, including maleated polypropylenes andethylene-propylene copolymers available as EXXELOR™ PO and maleicanhydride-functionalized ethylene-propylene copolymer rubber comprisingabout 0.6 weight percent pendant succinic anhydride groups, such asEXXELOR® VA 1801 from the Exxon Mobil Chemical Company;acrylate-modified polyethylenes available as SURLYN®, such as SURLYN®9920, methacrylic acid-modified polyethylene from the DuPont Company;and PRIMACOR®, such as PRIMACOR® 1410 XT, acrylic acid-modifiedpolyethylene, from the Dow Chemical Company; maleic anhydride-modifiedstyrene-ethylene-butylene-styrene (SEBS) block copolymer, such asKRATON® FG1901X, a SEBS that has been grafted with about 2 weight %maleic anhydride, available from Kraton Polymers; maleicanhydride-functionalized ethylene-propylene-diene monomer (EPDM)terpolymer rubber, such as ROYALTUF® 498, a 1% maleic anhydridefunctionalized EPDM, available from the Crompton Corporation. The filmsof the present invention are not limited to only those formed with theseimpact modifiers. Suitable functional groups on the impact modifierinclude any chemical moieties that can react with end groups of thepolyamide to provide enhanced adhesion to the high temperature matrix.

Other functionalized impact modifiers that may also be used in thepractice of the invention include ethylene-higher alpha-olefin polymersand ethylene-higher alpha-olefin-diene polymers that have been providedwith reactive functionality by being grafted or copolymerized withsuitable reactive carboxylic acids or their derivatives such as, forexample, acrylic acid, methacrylic acid, maleic anhydride or theiresters, and will have a tensile modulus up to about 50,000 psidetermined according to ASTM D-638. Suitable higher alpha-olefinsinclude C₃ to C₈ alpha-olefins such as, for example, propylene,butene-1, hexene-1 and styrene. Alternatively, copolymers havingstructures comprising such units may also be obtained by hydrogenationof suitable homopolymers and copolymers of polymerized 1-3 dienemonomers. For example, polybutadienes having varying levels of pendantvinyl units are readily obtained, and these may be hydrogenated toprovide ethylene-butene copolymer structures. Similarly, hydrogenationof polyisoprenes may be employed to provide equivalentethylene-isobutylene copolymers. The functionalized polyolefins that maybe used in the present invention include those having a melt index inthe range of about 0.5 to about 200 g/10 min.

Suitable dienes for use in the preparation ofethylene-alpha-olefin-diene terpolymers are non-conjugated dienes having4 to about 24 carbon atoms, examples of which include 1,4-hexadiene,dicyclopentadiene and alkylidene norbornenes such as5-ethylidene-2-norbornene. Mole fractions of ethylene units and higheralpha-olefin units in the ethylene-higher alpha-olefin copolymer rubbersgenerally range from about 40:60 to about 95:5. Ethylene-propylenecopolymers having about 50 to about 95 mole percent ethylene units andabout 5 to about 50 mole % propylene units are included among these. Interpolymers comprising polymerized diene monomer, the diene unit contentcan range up to about 10 mole %, and about 1 to about 5 mole % incertain embodiments. Also suitable are the corresponding blockcopolymers comprising two or more polymeric blocks, each formed of oneor more monomers selected from ethylene and the higher alpha-olefin. Thefunctionalized polyolefins will generally further comprise about 0.1 toabout 10 weight percent functional groups.

Other impact modifiers useful herein include those described in U.S.Pat. No. 6,765,062 (Ciba Specialty Chemicals Corporation) and EP 901 507B1 (DuPont).

Still other impact modifiers useful herein include acrylic impactmodifiers commercialized as Paraloid® impact modifiers by Rohm & Haas.

The amount of impact modifier present in composition L1 is not limitedand will preferably be a quantity sufficient to impart sufficienttensile elongation at yield and break. Generally, polyamide compositionL1 will comprise from about 2 weight % to about 40 weight % impactmodifier, based on total weight of composition L1, including for example5, 10, 15, 20, 25, 30 and 35 weight %. However, the impact modifier canbe present in amounts as little as, e.g., 0.1 weight %.

The impact modifier and aromatic polyamide can be mixed together in anymanner, and mixing can occur before, e.g., extrusion, or the materialsmay be mixed in the extruder.

Of course, more than one impact modifier may be used in Polyamidecomposition L1.

Polyamide Composition L2

The L2 polyamide compositions useful herein form optional layers of theinvention film and comprise an aliphatic polyamide. Aliphatic polyamidesare polymers comprising more than 50 mol % of “Type 2” repeating units,based on 100 mol % repeating units in the polymer. Type 2 repeatingunits have at least one CONH group in the polymer chain. In addition,Type 2 repeating units are characterized in that less than 30 mol %thereof comprise an aromatic group. Thus, the maximum content ofaromatic group-containing repeating units in an aliphatic polyamideherein is less than 15 mol % based on 100 mol % repeating units in thepolymer. Preferably, the aliphatic polyamide comprises more than 85 mol%, for example 90%, etc., based on 100 mol % of monomers making up thepolyamide, of monomers comprising an aliphatic group and having noaromatic group. Although not required, such aliphatic groups mayoriginate in a diamine monomer, and include aliphatic diaminescomprising 4 to 12 carbon atoms, such as hexamethylene diamine (HMDA),nonane diamine, 2-methyl-1,5 pentadiamine, and 1,4-diaminobutane, etc.One useful diacid source of aliphatic units is adipic acid. Usefulexamples of invention aliphatic L2 polyamides include aliphatic nylon(e.g., PA6, PA6,6, PA6,12, PA4,6, PA11, PA12, etc.).

Of course, more than one aliphatic polyamide may be used in polyamidecomposition L2. In addition, the impact modifiers described above may beused in polyamide composition L2 if desired.

Additives

Polyamide compositions L1 and L2 may each, individually, optionallyfurther contain one or more additives. Useful additives include, forexample, an external lubricant, such as PTFE or low density polyethylene(LDPE), to facilitate extrusion. Suitable powdered PTFE includePOLYMIST® F5A available from Solvay Solexis.

Another useful additive is a heat stabilizer. Suitable heat stabilizersinclude copper-containing stabilizers comprising a copper compoundsoluble in the polyamide and an alkali metal halide. More particularly,in certain embodiments the stabilizer comprises a copper (I) salt, forexample cuprous acetate, cuprous stearate, a cuprous organic complexcompound such as copper acetylacetonate, a cuprous halide or the like,and an alkali metal halide. In certain embodiments of the presentinvention, the stabilizer comprises a copper halide selected from copperiodide and copper bromide and an alkali metal halide selected from theiodides and bromides of lithium, sodium, and potassium. Formulationscomprising copper (I) halide, an alkali metal halide and a phosphoruscompound can also be employed to improve the stability of films formedfrom polyphthalamide compositions during extended exposure totemperatures up to about 140° C. The amount of the stabilizer used ispreferably that amount sufficient to provide a level of from about 50ppm to about 1000 ppm copper. Preferred compositions of the inventioncomprise an alkali metal halide and copper (I) halide at a weight ratiothe range of from about 2.5 to about 10, and most preferably from about8 to about 10. Generally, the combined weight of copper and alkali metalhalide compound in a stabilized polyamide composition ranges from about0.01 weight % to about 2.5 weight %. In certain other stabilizedpolyamide compositions used to form films according to the presentinvention, the stabilizer is present in the range of from about 0.1weight % to about 1.5 weight %.

A particularly suitable stabilizer for polyamide compositions accordingto the present invention comprises pellets of a 10:1 by weight mixtureof potassium iodide and cuprous iodide with a magnesium stearate binder.The potassium iodide/cuprous iodide heat stabilizer provides protectionagainst long term heat aging, such as exposure to under-the-hoodautomobile temperatures.

Another useful additive is a filler such as a reinforcing filler, orstructural fiber. Structural fibers useful in forming filled articlesand composite products include glass fiber, carbon or graphite fibersand fibers formed of silicon carbide, alumina, titania, boron and thelike, as well as fibers formed from high temperature engineering resinssuch as, for example, poly(benzothiazole), poly(benzimidazole),polyarylates, poly(benzoxazole), aromatic polyamides, polyaryl ethersand the like, and may include mixtures comprising two or more suchfibers. Suitable fibers useful herein include glass fibers, carbonfibers and aromatic polyamide fibers such as the fibers sold by theDuPont Company under the trade name KEVLAR®.

Another useful additive is an antioxidant. Useful antioxidants includeNauguard 445, phenols (for ex. Irganox 1010, Irganox 1098 from Ciba),phosphites, phosphonites (e.g., Irgafos 168 from Ciba, P-EPQ fromClariant or Ciba), thiosynergists (e.g., Lowinox DSTDP from GreatLakes), hindered amine stabilizers (e.g., Chimasorb 944 from Ciba),hydroxylamines, benzofuranone derivatives, acryloyl modified phenols,etc.

Other fillers which may also be used in polyamide compositions accordingto the invention include antistatic additives such as carbon powders,multi-wall carbon nanotubes and single wall nanotubes as well as flake,spherical and fibrous particulate filler reinforcements and nucleatingagents such as talc, mica, titanium dioxide, potassium titanate, silica,kaolin, chalk, alumina, mineral fillers, and the like. The fillers andstructural fiber may be used alone or in any combination.

Further useful additives include, without limitation, pigments, dyes,flame retardants, and the like, including those additives commonly usedin the resin arts. The additives may be employed alone or in anycombination, as needed. For particular applications, it may also beuseful to include plasticizers, lubricants, and mold release agents, aswell as thermal, oxidative and light stabilizers, and the like. Thelevels of such additives can be determined for the particular useenvisioned by one of ordinary skill in the art in view of thisdisclosure.

Methods

The invention films may be made by any technique known in the art orlater developed, including in particular, extrusion. In this regard, oneof ordinary skill in the art is capable of forming the films of theinvention as described herein using polyamide compositions L1 and L2 inview of this disclosure.

The physical dimensions of the film of the invention are not limited.Preferred thicknesses of single layer films or multilayer films rangefrom 5 microns to 1000 microns (0.05 to 1 mm), more preferably 15microns to 900 microns (0.15 mm to 0.9 mm), including all values andranges there between, notably 50, 100, 200, 400, 600 and 800 microns.

Films of the invention of impact modified polyamide can be extruded inthe normal manner, for example on existing film lines, and can providevery thin films (e.g., 5 to 50 microns) if desired. As discussed above,the films can be mono- or multi-layered. Properties of the films can bevaried by varying the proportions of materials making up the film, andby varying the filming process. Two layer films having construction ofdifferent L1's or L1/L2 can be produced without the need of tie layers.Three or more than three layer films can also be prepared. Excellentresults have been obtained notably with:

-   -   films comprising, as sole layer(s), at least one layer L1;    -   films comprising, as sole layer, one L1 layer (monolayer films);    -   films comprising, as sole layers, at least two L1 layers;    -   films comprising, as sole layers, at least one layer L1 and at        least one layer L2;    -   films comprising, as sole layers, two layers, the first one        being a L1 layer and the other one being a L2 layer (bilayer        films); in said films, L1 can either be the inner or the outer        layer;    -   films comprising, as sole layers, three layers of L1/L2/L1,        wherein L1 is both an inner and outer layer and L2 is the        intermediate layer.

Films of the invention have high tensile properties and high impactstrength; and show good resistance to abrasion. Mechanical strength,stiffness and tear strength are enhanced by biaxial orientation. Thus,films of the invention can be employed in a variety of situations wherepolyamide films are usually employed but provide better performance.

Films of the invention pick up water slower than and have a lowertransmission rate relative to conventional polyamide films (PA 6 or PA66). Thus, films of the invention, in one embodiment, can be used in hotwater applications where low permeation and higher temperature isrequired.

Films of the invention also have significantly lower permeation ratesfor fuel, and gases than conventional polyamide films such as polyamide12, 11, 6 or 66 films. Thus, in another embodiment, films of theinvention can be used at higher temperature and can be used in hightemperature fuel system applications, and particularly at highertemperatures than conventional polyamide films.

In another embodiment, films of the invention can be used usable asinsulating devices in electric motors and other electronic devices. Theuse of films of the invention in electronic applications is enhanced bythe higher thermal performance and stable electrical properties in highhumidity relative to conventional polyamide films such as PA 12, PA 11PA 66 or PA 6.

In another embodiment, films of the invention can be used as a substratefor flexible printed circuits and tape automated bonded laminates. Alaminate may be bonded on both sides of the film and use known acrylicsor epoxies to accomplish for the bonding.

Films of the invention can also be used in industrial transformers forinsulators and compressor motor coil insulators, etc.

Films of the invention have excellent chemical resistance to a widevariety of materials such as esters, ketones, weak acids, aliphatic andaromatic hydrocarbons etc. Unlike aliphatic conventional polyamides,such as PA 6 or 66, films of the present invention have good resistanceto alcohols. Thus, in another embodiment, films of the invention can beused as corrosion resistant barriers in the manufacture or preparationof chemicals.

EXAMPLES

Provided below are examples illustrative of the present invention, butnot limitative thereof.

Table 1 describes two compositions. In addition, a control compositionC1 was prepared of unmodified AMODEL® A-1006 PPA.

TABLE 1 Polyphthalamide Compositions Component Example 1 Example 2Amodel ® A-1004 PPA (wt. %) 75.75 74.75 maleic anhydride functionalizedEPDM 0 25 (wt. %) maleic anhydride functionalized SEBS 25 0 (wt. %)Powdered PTFE (wt %) 0.25 0.25 Total 100 100

Films of Examples 1, 2 and C1 were produced by extrusion. For theseexamples, the films were produced by co-extrusion/encapsulation. The setup for this process is shown in FIG. 1. Two 30 mm extruders were used E1and E2. Standard polyethylene and polyamide screws were used. Theextruders were connected to a T-die via a feed block.

The PPA pellets were in extruder E1 and a high viscosity pipe grade ofpolyethylene (Eltex® B4922) was in E2. The PPA film was encapsulatedbetween the polyethylene. There was no adhesion of the PPA film to thepolyethylene film. Peeling of the central PPA layer from the HDPE layerswas easy. Set up conditions are shown in Table 2.

TABLE 2 Example 1 Example 2 C1 Extruder E1 Z1 280 280 280 Z2 315 300 315Z3 325 330 325 Z4 325 300 325 Extruder E2 Z1 150 280 150 Z2 295 300 295Z3 325 330 325 Z4 325 330 325 Feed block 325 330 325 Die 325 330 325

Depending on the screw speed and the die separation films of Example 1and 2 and the control C1 from 50 to 300 microns in thickness could beobtained.

ISO 1 BA tensile specimens were punched from the films. They wereelongated at a crosshead speed of 0.5 mm/min and tested under theconditions of ISO 527. As shown below in Table 3, impact modificationprovides polymer compositions that have higher average tensileelongation at yield and break over unmodified control C1. In fact,invention PPA compositions comprising impact modifier have tensileelongation at yield and break more than twice as high as control. Thehigher tensile elongation at yield and break provides greater latitudein the processing parameters for barrier applications and thermoformingapplications of the present invention.

TABLE 3 Examples 1 2 C1 Impact Modifier SEBS EPDM Unmodified TestTemperature (° C.) 23 23 23 Prior Conditioning Dry as molded Dry asmolded 23° C./ 50% RH Average Tensile Elongation at Yield (%) 7.7 9.33.0 Average Tensile Elongation at Break (%) 154 169 66Film Extrusion without Encapsulation

Formulation Example 2 was run on an 18 mm Brabender single screwmachine. Set up is similar to FIG. 1 with exception that the T-die wasreplaced with a 100 mm wide slit die.

A standard polyamide screw was used. Barrel settings from rear to frontwere from 250 to 330° C. With a screw RPM of 25 mm and a torque of 4 kN,films of 50-150 microns thickness were obtained depending on the rollspeed.

Large Scale Film Extrusion

Formulation Example 2 was run on commercial size (76 mm diameter) singlescrew equipment. The screw was a 20:1/L/D with a 3:1 compression ratio.Rolls were heated to 125° C. Barrel settings from rear to front were setfrom 310 to 325° C. The adapter and die were set at 330° C. With a screwspeed of 70 rpm, film of 0.4 mm thickness was produced at rates of 2 to7 meter/minute depending on the head pressure.

Tensile properties of the film above were measured by ASTM D638:Tensile strength @ Yield=54.6 MPa

Elongation @ Yield=5.2%

Tensile strength @ Break=67.8 MPa

Elongation @ Break=110%

This demonstrates clearly the commercial utility in the manufacturer ofan impact modified polyphthalamide film and that the properties areacceptable for intended end use.

Barrier Properties

Fuel permeation tests were conducted on the Example compositions,control, and comparative compositions. The results of the fuelpermeation tests are shown in Table 4 below. The fuel permeation testswere performed on films from the same specimens as those listed in Table3.

In addition to impact modified compositions Examples 1 and 2,permeability measurements were also carried out on PA 12, PA 6, Solef®1010 PVDF and C1 (Amodel A-1006).

The fuel tested is CTF1, a 45/45/10 by volume isooctane/toluene/ethanolblend. See standard SAE J1681 rev. January 2000.

The measured fuel permeability is expressed as the number of grams ofpermeant that would permeate through a sheet of thickness 1 mm thicknessand a surface area of 1 m² sheet in a 1 day period. The permeability ofthe impact modified PPA, Examples 1 and 2, is far superior to aliphaticpolyamides (PA 6 and PA 12) and similar to PVDF.

Despite the fact that the incorporation of elastomers in the PPAcompositions of the invention is generally thought to be detrimental tothe barrier properties of PPA, very good barrier properties areretained.

TABLE 4 Total Permeation CTF1 fuel @ 60° C. Avg. Thickness FactorExamples μm g · mm/m² · day C1, Control, A-1006 58 0.03 Example 1 511.86 Example 2 98 1.95 PVDF Solvay Solef ® 1010 50 2.5 PA 6, Capron ®DF200 52 14.5 PA 12, Vestamid ® L2140 50 98.1

Thermoforming

Films of Example 2 of thickness 0.4 mm were successfully thermoformed. Asquare piece of film is clamped into a frame, similar to the canvas of apicture. The frame is indexed into an oven at 290 to 300° C. for 15-45seconds. The frame indexes from the oven directly over the tool. Once inposition the tool is raised pushing up and thermoform the film into thedesired article. Temperatures less than 280° C. cause the film to be toorigid to be formed. A temperature greater than 305° C. caused the filmto blister or melt.

Stamping

Films of Example 2 of thickness 0.4 mm were successfully stamped into avariety of shapes using commercial equipment. This technique is usefulfor the forming of flexible circuit boards for the electronics industry.

Heat Aging Comparisons with PA12

Table 5 describes two heat stabilized compositions (Example 3 andExample 4).

TABLE 5 Polyphthalamide Compositions Component Example 3 Example 4Amodel ® A-1004 PPA (wt. %) 74.18 73.18 maleic anhydride functionalizedEPDM 0 25 (wt. %) maleic anhydride functionalized SEBS 24 0 (wt. %) 10/1KI/CuI stabilizer (wt % 1.57 1.57 Powdered PTFE (wt %) 0.25 0.25 Total100 100

A comparison of the compositions according to Examples 3 and 4 with heatstabilized PA12 is provided in Table 6.

TABLE 6 Izod Impact (ft-lbs/in.) Strength After 255 Hours at TemperatureExamples 23° C. (Initial) 140° C. 150° C. 160° C. PA12 Heat Stabilized20.46 0.67 0.69 0.16 Example 3 19.73 17.07 15.02 12.47 Example 4 19.817.07 14.99 11.77

As can be seen, the PA12 undergoes a catastrophic loss in Izod impactstrength after heat aging. Consequently, the partially aromatic impactmodified polyamides are a much safer choice for retention of impactproperties after long term exposure to elevated temperatures in thepresence of air.

As described herein, in certain embodiments of the present invention,the film comprises a monolayer structure of the L1 composition. As usedherein, a “monolayer” is formed from single layer of a polymercomposition wherein the polymer composition is substantially the sameacross the entire thickness of the layer. In certain embodiments of thepresent invention, the thickness of the monolayer can range from about0.05 mm to about 1.0 mm. In certain embodiments of the presentinvention, the monolayer thickness ranges from about 0.15 mm to 0.9 mm.

The films can have surfaces that are rough, smooth, corrugated, etc.that are of a constant thickness throughout or a variable thickness,etc. In addition, the invention films can be used to enclose orencapsulate a content, and the content can vary widely. For example, thefilm of the invention can be used as a protection system. In this regardthe invention is also disclosed as actually containing or holding itsintended content.

The above written description of the invention provides a manner andprocess of making and using it such that any person skilled in this artis enabled to make and use the same, this enablement being provided inparticular for the subject matter of the appended claims, which make upa part of the original description and including a film comprising, assole layers,

-   (1) at least one layer L1 comprising an aromatic polyamide and an    impact modifier, and, optionally,-   (2) at least one layer L2 comprising an aliphatic polyamide.

Similarly enabled preferred embodiments of the invention include filmswherein the aromatic polyamide is a polyphthalamide; the aliphaticpolyamide is an aliphatic nylon; the impact modifier is selected fromthe group consisting of EPDM, SEBS, and mixtures thereof; the aromaticpolyamide is a polyamide having at least 50 mol. % of recurring unitsobtained by a polycondensation reaction between at least onedicarboxylic acid selected from the group consisting of phthalic,terephthalic, and isophthalic acids and mixtures thereof and at leastone aliphatic diamine; the polyphthalamide comprises from about 50 mole% to about 95 mole % hexamethylene terephthalamide units, from about 25mole % to about 0 mole % hexamethylene isophthalamide units, and fromabout 50 mole % to about 5 mole % hexamethylene adipamide units; theimpact modifier is a rubber; the rubber is a functionalizedpolyolefin-based rubber; the functionalized polyolefin-based rubber is amaleic anhydride functionalized styrene-ethylene-butylene-styrene blockcopolymer; the functionalized polyolefin based rubber is a maleicanhydride functionalized ethylene-propylene-diene monomer rubber; thelayers are contiguous layers of the order [(L1)_(n)/(L2)_(m)]_(x) wherex is any integer of 1 or greater, n is any integer of 1 or greater, andm is any integer; the layer L1 further comprises an external lubricant;the external lubricant is selected from the group consisting ofpolytetrafluoroethylene, low density polyethylene, and mixtures thereof;layer L1 further comprises a heat stabilizer comprising at least onecopper (I) salt and at least one alkali metal halide; the heatstabilizer comprises at least one copper halide selected from the groupconsisting of copper iodide and copper bromide and at least one alkalimetal halide selected from the group consisting of the iodides andbromides of lithium, sodium, and potassium; the film consists of, assole layer, a monolayer comprising an aromatic polyamide and an impactmodifier; and a method for making a film comprising, as sole layers,

-   (1) at least one layer L1 comprising an aromatic polyamide and an    impact modifier, and, optionally,-   (2) at least one layer L2 comprising an aliphatic polyamide,    comprising extruding an aromatic polyamide and an impact modifier,    and optionally extruding an aliphatic polyamide.

As used herein, where a certain polymer is noted as being “obtainedfrom” or “comprising”, etc. one or more monomers (or monomer units) thisdescription is of the finished polymer material itself and the repeatingunits therein that make up, in whole or part, this finished product. Oneof ordinary skill in the art understands that, speaking precisely, apolymer does not include individual, unreacted “monomers,” but insteadis made up of repeating units derived from reacted monomers.

All references, patents, applications, tests, standards, documents,publications, brochures, texts, articles, etc. mentioned herein areincorporated herein by reference. Similarly, all brochures, technicalinformation sheets, etc. for all commercially available materials areincorporated herein by reference. Where a numerical limit or range isstated, the endpoints are included. Also, all values and subrangeswithin a numerical limit or range are specifically included as ifexplicitly written out.

The above description is presented to enable a person skilled in the artto make and use the invention, and is provided in the context of aparticular application and its requirements. Various modifications tothe preferred embodiments will be readily apparent to those skilled inthe art, and the generic principles defined herein may be applied toother embodiments and applications without departing from the spirit andscope of the invention. Thus, this invention is not intended to belimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features disclosed herein.

1. A method for making a film comprising, as sole layer(s), at least onelayer L1 consisting of a polyamide composition comprising an aromaticpolyamide and an impact modifier, said method comprising extruding thepolyamide composition into the film.
 2. The method according to claim 1,wherein said aromatic polyamide is a polyphthalamide.
 3. The methodaccording to claim 2, wherein the polyphthalamide comprises from about50 mole % to about 95 mole % hexamethylene terephthalamide units, fromabout 25 mole % to about 0 mole % hexamethylene isophthalamide units,and from about 50 mole % to about 5 mole % hexamethylene adipamideunits.
 4. The method according to claim 1, wherein the impact modifieris a rubber.
 5. The method according to claim 4, wherein the rubber is afunctionalized polyolefin-based rubber.
 6. The method according to claim5, wherein the functionalized polyolefin-based rubber is a maleicanhydride functionalized styrene-ethylene-butylene-styrene blockcopolymer or a functionalized polyolefin based rubber is a maleicanhydride functionalized ethylene-propylene-diene monomer rubber.
 7. Themethod according to claim 1, wherein said layer L1 further comprisingpolytetrafluoroethylene.
 8. A method for making a film comprising, assole layers, at least two layers L1 consisting of a polyamidecomposition comprising an aromatic polyamide and an impact modifier,said method comprising extruding the polyamide composition into thefilm.
 9. A method for making a film comprising, as sole layer, one layerL1 consisting of a polyamide composition comprising an aromaticpolyamide and an impact modifier, said method comprising extruding thepolyamide composition into the film.
 10. The method according to claim9, wherein said aromatic polyamide is a polyphthalamide.
 11. The methodaccording to claim 10, wherein the polyphthalamide comprises from about50 mole % to about 95 mole % hexamethylene terephthalamide units, fromabout 25 mole % to about 0 mole % hexamethylene isophthalamide units,and from about 50 mole % to about 5 mole % hexamethylene adipamideunits.
 12. The method according to claim 9, wherein the impact modifieris a rubber.
 13. The method according to claim 12, wherein the rubber isa functionalized polyolefin-based rubber.
 14. The method according toclaim 13, wherein the functionalized polyolefin-based rubber is a maleicanhydride functionalized styrene-ethylene-butylene-styrene blockcopolymer or a functionalized polyolefin based rubber is a maleicanhydride functionalized ethylene-propylene-diene monomer rubber. 15.The method according to claim 9, wherein said layer L1 furthercomprising polytetrafluoroethylene.
 16. The method according to claim 9,wherein the thickness of the film ranges from 5 to 1000 microns.
 17. Themethod according to claim 16, wherein the thickness of the film rangesfrom 15 to 400 microns.
 18. The method according to claim 17, whereinthe thickness of the film ranges from 50 to 300 microns.
 19. The methodaccording to claim 18, wherein the thickness of the film ranges from 50to 150 microns.
 20. The method according to claim 16, wherein thethickness of the film ranges from 5 to 50 microns.